Process of producing steel



Patented Feb. 20, 1934 UNITED STATES PATENT OFFICE .MinnesotaMetallurgical 00.,

Minn, a corporation Minneapolis, of Minnesota No Drawing. ApplicationApril 14, 1932 Serial No. 605,351

5 Claims.

My invention relates particularly to the reduction of iron ore admixedwith the ores of other metals, and provides an improved process wherebyiron and its alloys, by a single or one-step process,

may be reduced to the form of steel, either pure steel or steel alloy.The steel or steel alloy thus produced may, by certain variations of theprocess, be brought down in various forms ranging from what is properlydesignated as a soft or mild steel to'a very hard steel, such as toolsteel or even a harder steel, and to a degree of hardness and tensilestrength which resists cutting and forging. The process can be bestcarried out in an electrical induction furnace, (although the H processis not limited to the use of such a furnace) in which the ores and thereducing agents and flux hereinafter described, should be placed beforethe heat is turned entirely on to the furnace.

For several years I have been engaged in experimenting with the processdisclosed and claimed in Letters Patent of the United States, No.1,850,381, issued to George A. Code of date March 22, 1932; and in myexperiments I have discovered that the salts of certain acids may beutilized with as good and in many instances,

better results than with the acids.

Before discussing the broad features of the invention, I will describein detail one of the several successful ways in which the process hasbeen carried out in actual practice. It is understood that I am notlimited in my invention by the exact proportion of reacting materials,by the time or by the exact temperature cited in the example givenbelow. 1

Example Into the furnace place twenty-five (25) grams of a salt of mucicacid, such as sodium mucate, then place therein approximately fifteen(15) pounds of dressed ore (e. g. 63% iron content), such for example,as comes direct from Minnesota mines. On top of the above mixture placea flux consisting of two and one-half (2 /2) pounds of lime and onehundred (100) grams fluorspar. Turn on the heat to produce temperaturesas follows:

First hour, twenty-five hundred (2500) degrees F.; second hour, twothousand six hundred fifty (2650) degrees F.; third hour, two thousandeight hundred fifty (2850) degrees F.; and during approximately one-halfof the fourth hour a furnace temperature of two thousand nine hundred(2900) degrees F.

During the last approximate half hour in the above process, if the steelis found deficient in the requisite amount of carbon, a proper amount ofcharcoal can be mixed into the molten mass, or if too much carbon ispresent, the high temperature can be maintained until a properpercentage 01' carbon in the molten steel is attained. The abovesuggested addition of carbon is not for the purpose of reduction, but tosupply a carbon content necessary for the inter-crystalline cement ofthe steel. In many instances, the addition of further carbon will not benecessary.

The end product produced by the above process, where the metal of theore is entirely iron will be a true steel, but where the ore containsother metals such as manganese, nickel, cobalt, cop-' per, tungsten,vanadium, chromium, lead etc.,the end product will be as'teel alloy; butthe final product will be produced by a single step process, asdistinguished from a two-step process such as has been hitherto employedand wherein the ore is first reduced to pig iron, and by a second step,is reduced from pig iron to the form of a steel or to a steel alloy.

I am unable to state the exact chemical or physical reactions that takeplace in the above process, but the results of the process have beendefinitely established. The fact that the desired results have been andmay be attained by quantities of reducing agencies which in themselvesare too small (as small as three-fourths of one per cent) for therequirements of the accepted chemical equations depicting the reductionof iron ore, seems to indicate that the organic compound which is added,or some subsequent decomposition product of such added organic compound,is the active agent and acts as a catalyst.

To date, I have obtained the best results by the use of a salt of mucicacid, such as sodium mucate, which, of course, is an organic compound;but I have obtained results differing only in degree by the use of otherorganic salts which are more or less closely related in their chemicalstructure to salts of mucic acid, such as salts of citric acid, tartaricacid, and oxalic acid. These substances are all salts of polycarboxylicacids. The polycarboxylic acid salts employed may or may not contain oneor more substituted groups in the organic acid. I have found thatvarious different polycarboxylic acid salts will combine with the fluxto produce the desired action with the general results above stated, butso far as my present experiments have gone, the polycarboxylic acidsalts which produce the above action in the flux are of the aliphitic orchain type. As to time and temperature, I have found that while underthe conditions of my experimentation, the best results can be obtainedby quite closely following the instructions of the above given Example1, I do not wish to be limited to the exact temperatures and theconditions which are noted.

The results obtained indicate that the action of the organic reagent isa catalytic reaction hitherto unknown, and that, in connection with theflux or other elements present, such a process serves to free the ironfrom oxygen, but at the present date I am unable to state just what thiscatalytic agent is, or exactly in what manner it reacts. I do knowhowever, that by the use of a certain class of organic chemicalcompounds which, in themselves have insufficient carbon and hydrogencontent to efiect the reduction by exchange of their carbon and hydrogenelements, neverthelesathe reaction produced causes a disassociation ofthe oxygen from the iron ore at approximately the temperatures indicatedand by approximately the treatment outlined in the example above. Thisaction, for lack of a more definite term, I have designated as acatalytic action that causes a disassociation oi the oxygen from theiron ore, the iron of the ore being recoverable in the form of steel orof steel alloys in the event that the original ore batch contained otheradmixed metallic ores or oxides.

In practice, I have found that while the proportions of ingredients usedmay be greatly varied, that they should be kept within the followingranges of proportion, to wit: from fifteen (15) to thirty-five (35)grams of polycarboxylic acid salt for fifteen (15) pounds of ore.

I What I claim is:

1. The process or" reducing oxide iron ores and admixtures of ores tothe form of true steel and its alloys, which consists in melting the oreor ores while commingled with a flux and with a salt of polycarboxylicacid, and in which the polycarboxylic acid is in the proportion of fromfifteen (15) to thirty-five (35) grams to fifteen (15) pounds of ore.

2. The process of reducing oxide iron ores and admixtures of ores to theform of true steel and its alloys, which consists in melting the ore orores while commingled with a flux and with a salt of mucic acid, and inwhich the salt of-mucic acid is in the proportion of from fifteen (15)to thirty-five (35) grams to fifteen (15) pounds of ore.

3. The process of reducing oxide iron ores and admixtures of ores to theform of true steel and its alloys, which consists in melting the ore orores while connningled with a flux and with sodium mucate, and in whichthe sodium mucate is in the proportion of fifteen (15) to thirty-five(35) grams to fifteen (15) pounds of ore.

4. The process of reducing oxide iron ores and suitable admixtures ofores to the form of true steel orlstecl alloys, which consists inmelting the same while comniingled'with a salt of polycarhoxylic acidand a flux, and which acid, in the presence of the flux has the propertyof effecting a catalytic action that causes disassociation of thenon-metallic from the metallic substances, thereby reducing the same tothe form of steel or its alloys, and in which the salt of polycarboxylicacid is in the pro-portion of from fifteen (15) to thirty-five (35)grams to fifteen (15) pounds of ore.

5. The process of reducing oxide iron ores and admixtures of ores to theform of true steel and its alloys, which consists in melting the ore orores while commingled with a flux and with a salt of polycarboxylicacid, and in which process the polycarboxylic acid is in a quantity lessthan sufficient to directly react with the oxygen of the ore, but issufiicient to produce a catalytic action accomplished in the saidreduction.

WILLIAM J. POPI-IAIVI.

